This invention pertains to terminal connectors of electrical extension cord sets, and, more particularly is concerned with terminal connectors having protective safety devices.
The ubiquitary extension cord needs little introduction as to its use or function. A complete extension cord includes a plug, usually having two prongs; a cord, usually a pair of insulated wires several feet in length; and a terminal connector for receiving one or more electrical plug to power lamps, radios and television sets, small appliances and the like.
Extension cords are found in nearly every home, and by their nature are usually strung at floor level. This poses a danger to inquisitive young children, a population known to probe or ingest almost every conceivable object. The terminal connector may have unused ports into which conductive foreign objects such as paper clips, pins, and the like can be inserted. Such activity can easily result in electrical shock, injuring or perhaps killing the child. This danger has been recognized and extension cord manufacturers are providing safeguards in attempts to frustrate such misuse.
A common approach is the use of a pseudo-twin prong plug which blocks unused ports. Unfortunately youngsters appear to have no more difficulty than adults in removing this device.
Another approach is the use of a disc rotatably mounted to cover the electrical ports. The disc has slots which can be brought into register with the electrical ports. One such arrangement is described in U.S. Pat. No. 3,879,098 issued to Lawrence and Martin. This approach has been said to be more successful than the pseudo-twin prong plug, but can still be defeated by use of a foreign object to turn the disc.
Yet another approach is the use of movable plates to cover the electrical ports. The plates have slots which are intended to be misaligned with unused ports. One such arrangement is described in U.S. Pat. No. 3,810,070 issued to Ludwig. The plate is held to the connector body by flanges molded in the body. The body is resilient and urges the plate to a misaligned position. U.S. Pat. No. 4,094,569 issued to Dietz is another movable plate arrangement. Here the plate is secured to the connector body by a central barbed stake and is biased by a separate bowed spring. In the latter two arrangements, prongs of a plug are used as a tool to align the slots and ports for insertion of the plug. U.S. Pat. No. 4,206,957 issued to Ludwig and Tansi describes a plate guard molded with an integral spring approximately perpendicular to the center of the plate. The free end of the spring is inserted into the connector body and retains the cover. The plate is knurled on one side to facilitate manual manipulation of the plate.
All of the above safeguards do offer some protection from the danger of electrical shock. Unfortunately these safeguards can be defeated by unidirection movement of the covering member, and upon such a defeat, access to both electrical ports occurs simultaneously.
It will be appreciated that an ideal safeguard should be activated only by movement which is easy for an adult and difficult for a child.
A primary object of the invention is to provide a terminal connector having a safety cap, and which requires, for successful manipulation, the apposable capacity of the adult hand for which children lack the necessary strength and coordination.
A second object of the invention is to provide a terminal connector with a safety cap having features assuring proper and secure assembly of its components.